Internal combustion engines are commonly utilized to power the propeller of an outboard motor. In these types of motors, the engine is mounted in an enclosure formed by a cowling. The engine is oriented with its crankshaft vertically extending, with a bottom end of the crankshaft arranged to drive a drive shaft. This drive shaft extends through a lower portion of the motor to a transmission for selectively driving the propeller.
These types of motors are normally mounted to a transom portion of the hull of a watercraft at the stem of the craft. The motor is pivotally connected to the watercraft so that the depth of the propeller in the water may be adjusted, or the propeller may be entirely removed from the water.
In this arrangement, the cowling portion of the motor which houses the engine is generally above the pivot point or axis. Due to the weight of the engine, the pivoting of the motor can be rather difficult. It is, therefore, generally desirable for the engine to have as low of a center of gravity as possible.
This desire is made difficult by the orientation of the engine in which the crankshaft is vertically extending. In particular, a number of accessories or other engine features are often driven off of the crankshaft, and when these features are positioned at or above the top end of the engine the center of gravity is raised.
Another problem associated with the vertically extending crankshaft is that an excessively large bending force or moment may be applied to the crankshaft if it extends too far beyond the top or bottom of the engine and is used to drive other engine features. This may cause damage to the crankshaft, mounting bearings or the like.
It is, therefore, an object of the present invention to provide a camshaft and accessory drive arrangement for an engine powering an outboard motor where the drive arrangement reduces the bending forces applied to the crankshaft and maintains a lower engine center of gravity.